Comparison of Superconducting Properties of Bulk MgB2 Samples with Pyrene Additive Produced by B Powder and C encapsulated B Powder

In this paper, the advantages and disadvantages of using B powder and C encapsulated B powder as a precursor during the production process of MgB2 with the addition of pyrene (C16H10) were investigated. Two MgB2 bulk samples with the addition of 10 wt % C16H10 of 1 g MgB2 were produced by the in-situ method using B powder and C encapsulated B powder. The C encapsulated B powder as a precursor was prepared by adding 10% C16H10 as a C source. From XRD and SEM analysis, a greater increase in MgO phase and a greater decrease in a-lattice parameter were observed for the sample produced with B, compared to the sample produced with C encapsulated B. The curves of critical current density (J(c)) at 5 K showed a similar character for both samples. The J(c) values at 5 K in self field were respectively obtained as 1.52 x 10(5) A/cm(2) and 1.90 x 10(5) A/cm(2) for the samples produced by B and C encapsulated B. The decrement ratio of in-field J(c) at 20 K was less affected by increasing magnetic field for the sample produced using C encapsulated B due to the relatively higher increase in the irreversibility field (H-irr) and the upper critical magnetic field (H-c2) values. The J(c) values at 20 K and 3 T were respectively determined as 1.49 x 10(4) A/cm(2) and 1.93 x 10(4) A/cm(2) for the samples produced with B and C encapsulated B.